[59.22] X-rays and Protostars in the Trifid Nebula

The Trifid Nebula is a young HII region recently
rediscovered as a ``pre-Orion" star forming region,
containing protostars undergoing violent mass ejections
visible in optical jets as seen in images from the Infrared
Space Observatory and the Hubble Space Telescope. We report
the first X-ray observations of the Trifid nebula using
ROSAT and ASCA. The ROSAT image shows a dozen X-ray sources,
with the brightest X-ray source being the O7 star, HD
164492, which provides most of the ionization in the nebula.
We also identify 85 T Tauri star and young, massive star
candidates from near-infrared colors using the JHKs
color-color diagram from the Two Micron All Sky Survey
(2MASS). Ten X-ray sources have counterpart near-infrared
sources. The 2MASS stars and X-ray sources suggest there are
potentially numerous protostars in the young HII region of
the Trifid. ASCA moderate resolution spectroscopy of the
brightest source shows hard emission up to 10 keV with a
clearly detected Fe K line. The best model fit is a
two-temperature (T = 2.0\times 106 K and 36 \times
106 K) thermal model with additional warm absorbing
media. The hotter component has an unusually high
temperature for either an O star or an HII region; a typical
Galactic HII region could not be the primary source for such
hot temperature plasma and the Fe XXV line emission. We
suggest that the hot component originates in either the
interaction of the wind with another object (a companion
star or a dense region of the nebula) or from flares from
deeply embedded young stars.